In the present specification, an organic electronic diode is an electronic diode using an organic semiconductor material, and requires exchange of holes and/or electrons between an electrode and the organic semiconductor material. The organic electronic diode may be largely divided into the following two categories according to an operation principle. First, there is an electronic diode in which an exciton is formed in an organic layer by a photon that flows from an external light source to the diode, the exciton is separated into electrons and holes, and the electrons and the holes are transferred to the different electrodes and used as a current source (voltage source). Second, there is an electronic diode in which holes and/or electrons are injected into an organic semiconductor material layer forming an interface to the electrode by applying a voltage or a current to two or more electrodes to operate the diode by the injected electrons and holes.
Examples of the organic electronic diode comprise an organic light emitting diode, an organic solar cell, an organic photoconductor (OPC) drum, an organic transistor and the like, and all of the organic electronic diodes require electron/hole injection materials, electron/hole extraction materials, electron/hole transport materials or a light emitting material in order to drive the diode. Hereinafter, an organic light emitting diode will be mainly described in detail, but in the organic electronic diodes, all of the electron/hole injection materials, the electron/hole extraction materials, the electron/hole transport materials or the light emitting material are operated on the basis of the similar principle.
In general, an organic light emitting phenomenon means a phenomenon that converts electric energy into light energy by using an organic material. The organic light emitting diode using the organic light emitting phenomenon has a structure generally comprising an anode, a cathode, and an organic layer between the anode and the cathode. Herein, most organic layers have a multilayered structure constituted by different materials in order to increase efficiency and stability of the organic light emitting diode, and for example, may comprise a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer and the like. In the structure of the organic light emitting diode, if a voltage is applied between two electrodes, holes are injected from an anode and electrons are injected from a cathode to the organic layer, and when the injected holes and the electrons meet each other, an exciton is formed, and light is emitted when the exciton falls to a bottom state. It is known that this organic light emitting diode has properties such as magnetic light emission, high brightness, high efficiency, low driving voltage, a wide viewing angle, high contrast and high response speed.
In the organic light emitting diode, the material used in the organic layer may be classified into a light emitting material and a charge transport material, for example, a hole injection material, a hole transport material, an electron transport material, an electron injection material and the like according to a function thereof. The light emitting material is classified into blue, green, and red light emitting materials and yellow and orange light emitting materials required to realize better natural colors according to the light emitting color. Further, a host/dopant system may be used as the light emitting material in order to increase color purity and increase light emitting efficiency through transferring of energy. The principle is that if a small amount of dopant that has a smaller energy band gap than a host mainly forming the light emitting layer and excellent light emitting efficiency is mixed with the light emitting layer, the exciton generated in the host is transported to the dopant to emit light at high efficiency. In this case, since the wavelength of the host moves to the wavelength bandwidth of the dopant, a desired wavelength of light may be obtained according to the kind of used dopant.
In order to sufficiently show excellent properties of the aforementioned organic light emitting diode, a material constituting the organic layer in the diode, for example, the hole injection material, the hole transport material, the light emitting material, the electron transport material, the electron injection material and the like should be supported by stable and efficient materials in advance, but development of a stable and efficient organic layer material for organic light emitting diodes has not yet been sufficiently made, such that there is a demand for developing a new material.